Substituted 1, 3-dithianyl pentanoic acids



United States Patent SUBSTITUTED 1,3-DITHIANYL PENTANOIC ACIDS George H.Latliam, Forwood, DeL, Charles W. Todd, Westtown, Pa., and Winston J.Wayne, Center-ville, Del., assignors to E. I. du Pont de Nemours &Company, Wilmington, Del., a corporation of Delaware No Drawing.Application October 6, 1953, Serial No. 384,512

12 Claims. (Cl. 99163) This invention relates to new compositions ofmatter and, more particularly, to a new class of biologically activeorganic compounds.

a-Lipoic acid, the dexfrorotary form of -(1,2-dithiolane-3-y1)pentanoicacid, is a vitamin-like material intimately associated with thenutritional needs of various types of microorganisms (Present knowledgeof lipoic acid, Nutrition Reviews 11, 59 (1953)). This newly recognizedvitamin is not stable to oxidation and accordingly a more stablematerial exhibiting the biological activity of lipoic acid is desirable.

This invention has as an object the preparation of new compounds.materials capable of replacing lipoic acid in biological systems.Another object is the preparation of new inhibitors of rancidificationfor use in fats and oils. Still another object is the preparation ofedible glyceride compositions of greater stability towardsrancidification. Other objects will appear hereinafter.

These objects are accomplished by the present invention of5-(1,3-dithiane-4-yl)pentanoic acids and their derivafives of theformula in which R and R are hydrogen, monovalent hydrocarbon radicalsor together form a divalent hydrocarbon radical, and R" is hydroxyl or aradical hydrolyzable thereto. These compounds are much more stable tooxidation than is m-lipoic acid and further are highly useful asreplacements for lipoic acid.

The 5-(1,3-dithiane-4-yl)pentanoie acids of this invention are preparedby the reaction of 6,8-dimercaptooctanoic acid with an oxo compound, i.e., an aldehyde or ketone, in the presence of hydrogen chloride. Theresulting mercaptal or mercaptol is isolated and purified byrecrystallization, distillation or extraction with an organic solvent.6,8-dimercaptooctanoic acid may be prepared by the method of thecopending Acker and Todd application Ser. No. 325,236, filed December10, 1952.

The following examples in which parts are by weight are illustrative ofthe invention. The term N. E. below is used to indicate neutralizationequivalent.

Example I The mercaptal, 5-(2-phenyl-1,3-dithiane-4-yl)-penfanoic acid00115 was synthesized as follows:

A further object is the preparation of new 2,752,249 Patented June 26,1956 6,8-dimercaptooctanoic acid (500 parts), benzaldehyde (318 parts),and fused zinc chloride (50 parts) were mixed in a stoppered flask anddry hydrogen chloride gas bubbled through the mixture until it wassaturated. The introduction of the hydrogen chloride caused the reactionmixture to become warm and cloudy, indicating reaction was proceeding.After standing at room temperature for two days, the reaction mixturewas stirred with water and then extracted with ether. The ether was thenextracted with 5% sodium hydroxide solution to dissolve acidicmaterials. Acidification of the sodium hydroxide solution with 5%hydrochloric acid produced a yellow oil which was extracted away fromthe aqueous layer with ether. This ether extract was washed with wateruntil the washings were neutral and then dried over anhydrous sodiumsulfate in the cold. After removal of the drying agent and ether, ayellow oil remained which was distilled to yield 397 parts (56% yield)of a brown syrup with B. P. 195 C./O.51.2 mm., n 15681-15834. A middlecut with B. P. l95 C./ 0.6 mm. was analyzed.

Analysis.-Calculated for C15H2002S2Z C, 60.75%; H, 6.79%; S, 21.60%; N.E, 296. Found: C, 60.72%; H, 6.97%; S, 21.94%; N. E., 284.

This fraction crystallized on standing.

Example 11 The mercaptol, 5-(2,2-dimethyl-1,3-dithiane-4-yl)-pentanoicacid was prepared and isolated by a procedure similar to that in ExampleI. 6,8-dimercaptooctanoic acid (500 parts) was reacted with acetone (175parts) in the presence of fused zinc chloride (50 parts) and anhydroushydrogen chloride gas. The product was distilled to yield 413 parts(69.5% yield) of a light yellow syrup with B. P. 140152 C./0.1 mm., 111.5282 1.5298. A cut with B. P. 151152 C./0.1 mm. was analyzed.

Analysis.-Calculated for C11H20O2S2: C, 53.1%; H, 8.10%; S, 25.80%; N.E., 248. Found: C, 53.55%; H, 8.09%; S, 26.37%; N. E. 243.

Example 111 5-(2-methyl-1,3-dithiane-4-yl)-pentanoic acid was preparedas follows: 6,8-dimercaptooctanoic acid (500 parts), benzene (880parts), and fused zinc chloride (50 parts) were mixed in a stopperedflask and cooled with an icesalt mixture. Cold acetaldehyde (157 parts)was then added and anhydrous hydrogen chloride gas bubbled gentlythrough the reaction mixture. The mixture became cloudy and eventuallyformed two layers while standing for a day at 4 C. The reaction mixturewas worked up as described in Example I and the product distilled toyield 394 parts (70% yield) of a yellow syrup with B. P. 130 163C./.060.2 mm. This syrup crystallized on standing and was recrystallizedfrom cyclohexane to yield 196 parts of white solid, M. P. 84-87 C. whichwas analyzed,

Analysis.-Calculated for Ciel-1180252: C, 51.2%; H, 7.74%; S, 27.33%; N.E. 234. Found; C, 51.27%; H, 7.75%; S, 27.72%; N. 13., 234.3.

Example IV Ethyl 5-(2-methyl-l,3-dithiane-4-yl)pentanoate was preparedas follows: Ethyl 6,8-dimercaptooctanoate (500 parts), benzene (880parts), fused zinc chloride (5 0 parts) were mixed and cooled with anice-salt mixture. Cold acetaldehyde (157 parts) was then added andanhydrous hydrogen chloride gas bubbled gently through the reaction.After standing four to five hours at 4 C., the reaction mixture wasstirred with water and then extracted with ether. The ether layer wasextracted with 1% sodium hydroxide solution to remove acidic materials,washed with 5% hydrochloric acid and water, and dried over anhydroussodium sulfate in the cold. After removal of the drying agent and ether,the product was distilled to yield 300 parts (54% yield) of a yellow oilwith B. P. 120-136 C./0.08 mm., 12 1.51001.5l39. A middle cut with B. P.124-133 C./0.08 mm. was analyzed.v

Analysis.-Calculated for C12H22O2Sz: C, 54.9%; H, 8.44%; S, 24.41%; Sap.No.,. 213.5. Found: C, 55.09%; H, 8.33%; S, 24.55%; Sap. No, 216.9.

Example V -(2,2-diphenyl-1,3-dithiane-4-yl)pentanoic acid was preparedas follows: 6,8-dimercaptooctanoic acid (500 parts), benzophenone (.437parts), benzene (880 parts), and fused zinc chloride (50 parts) weremixed in a stoppered flask and. cooled in an ice bath. Anhydroushydrogen chloride gas was bubbled through the reaction mixture. The'reaction mixture became cloudy and eventually formed two layers whilestanding for three days at 4 C. The reaction mixture was worked up asdescribed in Example I except 2.5% sodium. hydroxide solution Was usedfor extracting the acidic components since 5% sodium hydroxide solutionappeared to salt out a solid sodium. salt. Removal of ether from thefinal dried solution left a light yellow syrup (about 600 parts) whichdid not distill at about 200 C. under 0.1 mm. reduced pressure. Theoriginal unheated light yellow syrup was analyzed.

Analysis.-Calculated for C21Hz4O2S2: C, 67.7%; H, 6.49%; S, 17.20%; N.E., 372.5. Found: C, 66.38%; H, 6.83%; S, 19.69%; N. B, 371.2.

Example VI 5-(l,3 dithiane-4-yl)pentanoic acid was synthesized asfollows: 6,8-dimercaptooctanoic acid (50 parts), 36% aqueousformaldehyde (25 parts), and 0.1 N aqueous hydrochloric acid (250 parts)were mixed in a flask equipped with a reflux condenser and the flaskflushed with nitrogen. The reaction mixture, consisting of a yellow oillayer and anaqueous layer, was refluxed for 1.5 hours. To the hotreaction mixture was then added peroxide-free dioxane (258 parts) and36% aqueous formaldehyde parts). A clear yellow homogeneous solutionresulted which was refluxed for one hour and then allowed to stand atroom temperature overnight. The reaction mixture, now consisting of twolayers, was worked up as described in Example 1'. Removal of ether fromthe final dried solution left a yellow oil which crystallized onstanding. When the product was subjected to distillation under reducedpressure, it appeared to decompose slightly at 200 C. Therefore, theattempted distillation was stopped. The product was then recrystallizedfrom a large quantity of cyclohexane to yield 7 parts of a white powder,M. P. 9798.5 C. This was analyzed.

Analysis.Calculated for C9H1sO2S2: C, 49.05%; H, 7.32%; S, 29.05%; N.E., 220. Found: C, 50.06%; H, 7.47%; S, 29.57%; N. E., 219.

Example VII 5 [1,5 dithiaspiro(5.5)hendecane 2 yl]pentanoic acid wassynthesized as follows: 6,8-dimercaptooctanoic acid (500 parts),cyclohexanone (235 parts) benzene (880 parts), and fused zinc chloride(50 parts) were mixed in a stoppered flask and cooled in an ice bath.Dry hydrogen chloride gas was then bubbled through the reaction mixture,The mixture became cloudy and formed two layers while standing for threedays at 4 C. The reaction mixture was worked up as described in ExampleI. Removal of the ether from the final dried solution left a yellow oilwhich crystallized. This solid wasrecrystallized from cyclohexane toyield 440 parts (63.5% yield) of 4. a cream-colored solid, M. P. 104-l06C. This solid was analyzed.

Analysis.Calculated for C14H24O2S2: C, 58.25%; H, 8.38%; S, 22.20%; N.B, 228.4. Found: C, 58.8%; H, 8.56%; S, 22.38%; N. E., 286-.

Example VIII 5-(1,3-dithiane-4-yl)pentanamide was synthesized asfollows: 5-(l,3-dithiane-4-yl)pentanoic acid parts), anhydrous pyridine(5 parts) and anhydrous toluene (3000 parts), were mixed in a flaskequipped with a nitrogen inlet, dropping funnel, and reflux condenserprotected with a calcium chloride drying tube. The flask was warmed todissolve the solid. acid and anhydrous nitrogen was bubbled slowlythrough the solution. The solution was then cooled in an ice bath to0-5" C. Thionyl chloride (54 parts) dissolved in anhydrous toluene (1000parts) was then run into the cold reaction mixture. The reaction mixturewas kept cold in an ice bathwhile anhydrous nitrogen was bubbled gentlythrough it for 19 hours. At the end of this time a slow stream ofanhydrous ammonia gas was passed over the cold, clear, slightly yellowsolution of 5-(1,3-dithiane-4-yl)pentanoyl chloride. A white solid beganto form immediately and the slow stream of ammonia was continued whilethe reaction mixture was kept cold and shaken occasionally during onehour. The reaction mixture was then allowed to warm to room temperature,mixed with water and extracted with ether. The ether extract was washedwith cold 3% hydrochloric acid, cold 1% sodium hydroxide solution, andwater and then dried over anyhdrous sodium sulfate. After removal of thedrying agent, the ether and toluene were removed under reduced pressureat 35 C., to leave a white solid. This solid was recrystallized fromabsolute ethanol to yield 23 parts (23% yield) of 5-(1,3-dithiane-4-yl)pentanamide in the form of white needles, M. P. 131132 C.

Analysis.Calculated' for C9H1'1OS2N: C, 49.3%; H, 7.81%; S, 29.20%; N,6.38%. Found: C, 50.0%; H, 7.81%; S, 27.96%; N, 6.06%.

Example IX The sodium salt of 5-(1,3-dithiane-4-yl)pentanoic acid wasprepared as follows: 5-(1,3-dithiane-4-yl)pentanoic acid (50 parts)dissolved in absolute methanol (1500 parts) has added to it 2 N sodiummethoxide in absolute methanol (86 parts). To the resulting clearsolution was added anhydrous ether (30,000 parts) whereupon a whitegel-like solid precipitated. The solid wasv crushed and separated fromthe reaction mixture by centrifuging. The solid was then washed threetimes by crushing it in anhydrous ether and separating it each time bycentrifuging. The gel-like solid was then freed of ether under reducedpressure at room temperature and dried in vacuo over calcium chloride toyield 46 parts (84% yield) of sodium 5-(1,3-dithiane-4-yl)-pentanoate inthe form of a white powder.

Analysis.Calculated for C9H15O2S2Na: S, 26.42%; Na, 9.48%. Found: S,25.96%; Na, 9.71%.

The white solid dissolved readily in water to form a clear neutralsolution.

The 5-(1,3-dithiane-4-yl)pentanoic acids of the present invention have,among their many utilities, the valuable property, when added toglycerides, i. e., fats and oils, of enhancing their stability towards,i. e., reducing the tendency towards, rancidification. This property isexemplified in ExamplesA and B below which clearly illustrate theexcellent stabilization against rancidity of edible corn oil and lardimparted by 1% of the tested compounds.

Example A A 50% solution of corn oil in benzene was divided into threeportions. One portion (Code 1) was kept as a control, a second portion(Code 2) was stabilized by the addition of 1% (of the weight of the cornoil) of 5-(ZQ-dimethyI-1,3-'dithiane-4-yl)peutanoic acid, and the thirdportion (Code 3) was stabilized by the addition of 1% (of the weight ofthe corn oil) of 5(2-phenyl-1,3- dithiane*4-yl)pentanoic acid. Pieces offilter paper were impregnated with the clear solutions, excess solutionblotted OE, and the filter paper air-dried for fifteen minutes. Thepapers were then placed in separate, closed glass bottles which werestored in a 65 C. oven. The bottles were opened daily and examined forthe development of rancid odor. The times for the initial detection of aslight odor of rancidity and for the development of a strong odor ofrancidity are noted in the following table.

Days Required for Rancidity to Develop at 65 C. Coating on Paper 523Slight Strong Rancid- Rancidity ity Corn Oil (control) 1 4 5 Corn Oil 1%5-(2,2-d1methy1-1,3-

dithiane-4-yl)pentanoic acid 2 23 24 Corn Oil 1%5-(2-phenyl-1,3-dithiane- 4-yl)pentanoic acid 3 35 Corn oil specimensstabilized respectively by the addi tion of 1% of5-(1,3-dithiane-4-yl)pentanoic acid, 1% of5-(Z-methyl-1,3-dithiane-4-yl)pentanoic acid and 1% of5-[1,5-dithiaspiro(5.5)hendecane-2-y1]pentanoic acid showed similarimprovement in resistance to rancidification over the control whentested as above.

Example B Days Required for Rancidity to Dey velop at 65 C. Coating onPaper gz g Slight Strong Raneid- Rancidity ity Lard (control) 4 4 6 Lard1% 5-(2-phenyl-1,e-dithlane-4-yl)- pentanoic acid 5 Lard 1%5-(2,2-dimethyI-1 3-dlthiane- 4-yl) pentanoic acid 6 1 N0 rancid odorafter 60 days.

While the rancidification inhibitive effect of the compounds of thepresent invention on corn oil and lard has been illustrated above theinhibition is generic to glycerides subject to rancidification includinganimal fats, such as butter, tallow, fish liver oil, fish oils, andwhale oil; vegetable fats and oils, such as coconut oil, palm oil,soybean oil, cocoa butter, olive oil, cottonseed oil, peanut oil,sunflower seed ,oil, castor oil, and partly hydrogenated oils of thesekinds.

In spite of the fact that the dithianes' of the present invention differso sharply from lipoic acid'in resistance to oxidation, thesedithianespossess to a remarkable degree the ability to activate the oxidativedecarboxylation of pyruvic acid by dried cells of Streptococcus faecalis1001. This is a most unexpected result since activation of thisoxidative degradation has been shown as a specific assay for lipoic acid(Gunsalus, Dolin and Struglia, J'. Biol. Chem, 194, 849-857 (1952)). Asis common in the field of biochemistry, this test is so highly specificthat only one optical isomer of 5-(1,2-dithiolane-3-yl)pentanoic acidresponds to it, the other optical isomer, as closely related a chemicalas can be visualized, being inactive. It is therefore most surprisingthat the 1,3-dithianes of the present invention, compounds in which theheterocyclic ring contains two thioether functional groups completelyseparated by hydrocarbon structure, should show a biological activityresembling that shown by a 1,2- dithiolane, a compound in which theheterocyclic ring contains a single disulfide functional group. Thisresult leads to speculation as to whether the 1,3-dithiane may in someway be metabolized to lipoic acid by the Streptococcus faecalis 10C1,but no information is available on this point and applicants do not wishto be limited by such speculation.

The activation of the oxidative decarboxylation of pyruvic acid by theproducts of the present invention in the test of Gunsalus et a1. isshown in the following table:

Weight of Oxygen Activator Activator Uptake 1 i e) I Lipoic acid5-(2-methyl-1,3-dithiane-4-yl)-pentanoic acid-.. 5 225-(2,2dimethyl-1,3-dithiane-4-yDpentanoic acid 5 23 5-(1,3-dithiane-4-yl)pentanoic acid 5 27 5-[1,5-dithiaspiro(5.5)hendecane-2-y1] pentanoic ac a a 5 18 Ethyl 5-(2-methyl-1,3-dith1ane-4-yl)pentanoate 6 37 1 Over and above the oxygenuptake of a simultaneous blank containing no activator.

The present invention is generic to compounds of the formula whereineach of R and R are hydrogen or a monovalent hydrocarbon radical or Rand R together form a divalent hydrocarbon radical. When either or bothRs are hydrocarbon they are preferably free from non-aromaticunsaturation and R" is hydroxyl or a radical hydrolyzable thereto.

The free acids of the present invention are converted to their metalsalts by dissolving the acid in an anhydrous alcohol such as methanoland adding a metal alkoxide such as sodium methylate, whereupon themetalsalt of the acid is precipitated. Ammonium salts of the free acids ofthe present invention are prepared by adding anhydrous ammonia to anether solution of the free acid. The free acids are converted to theacid chlorides by treatment with thionyl chloride in solution inaromatic hydrocarbons. The resulting acid chlorides are converted toamides by treatment with ammonia or amines in arcmatic hydrocarbonsolution. The acid chlorides are converted to esters by treatment withalcohols in aromatic hydrocarbon solution.

The products of the present invention can be prepared as illustrated inthe examples, by the reaction of an oxo compound RCOR wherein R and Rare each hydrogen or a monovalent hydrocarbon radical. Thusformaldehyde, acetaldehyde and alkanals in general; acetone andalkanones in general; benzaldehyde and arenals in general; benzophenoneand other arenones in general; cyclohexanone and cycloalkanones ingeneral can be employed. The substituents, R and R, on the carbonyl,when not hydrogen, are hydrocarbon either one monovalent or twomonovalent or one divalent hydrocarbon radical. The hydrocarbon radicalsare preferably free from nonaromatic, i. e., non-benzenoid, unsaturationbut unsaturated oxocompounds, e. g., cyclohexenone, methylvinyl ketone,'acrolein, cinnamaldehyd'e, or acraldehyde canbe used, thus furnishingunsaturated hydrocarbon radicals on thedithiane-pentanoi'c acid.

The reaction for the formation of the products of this invention can becarried out in the absence of a solvent, asin Examples I- and II, in thepresence of an inert organic solvent, as in Examples III, IV, V, andVII,or inthe presence of water, as in Example VI. It should be noted. that,in eachcase as the reaction proceeds, water is given offso that,regardless of the starting conditions, the reacting system does notremain anhydrous. The use of an acidic catalyst as illustrated byhydrogen chloride in Example VI and by a combination of zinc chlorideand hydrogen chloride in Examples I-V and VII is optional. The use of acatalyst is preferred since it leads to improved yields inshorter times,but the formation of mercaptals and: mercaptols as in these examplestakes place in the absence of such a catalyst.

The temperature employed in the above reactions can bevaried widely. Ingeneral, fewer side reactions are encountered when the reactions arecarried out at temperatures: belowroom temperature, althoughtemperatures up to the boiling point of the reaction mixture may beemployed.

The term carboxylic in the claims isused in the Patent Ofiice sense (C.B. 78, p. 19) to designate the COO- radical, i. e., that of acids,esters, anhydrides, and salts.. See alsoC. B. 74, p. 28; C. B. 200, pp.260-1; C. B. 85, p. 7.

The term spirocarbon designates the one carbon common to the two ringstructures of a spiro compound.

The term X0 denotes the presence of a carbonyl (C:O) bonded to hydrogenand/or carbon. and is a term generic to aldehydes and ketones(Classification Bulletin 200, pages 260-264).

The foregoing detailed description has been given for clearness ofunderstanding only and no unnecessary limitations are to be understoodtherefrom. The invention is not limited to the exact details shown anddescribed for obvious modifications will occur. to those skilled in theart.

What is claimed is:

I. A carboxylic heterocyclic compound of the formula wherein R" isselected from the class consisting of the carboxylic hydroxyl group andgroups hydrolyzable to such hydroxyl group and R and R when takenseparately are selected from the class consisting of hydrogen andmonovalent hydrocarbon radicals of not more than eight carbons and whentaken together form a divalent hydrocarbon radical of not more thaneight carbons.

2. A 1,3-dithiane having on the four carbon a normal butyl substituentwith a carboxylic group on the carbon furthest removed from the ring andhaving the extranuclear valences of carbons 4, 5, and 6 otherwisesatisfied by hydrogen.

3. A 1,3-dithiane having on the four carbon a normal butyl substituentwith a carboxylic group on the carbon furthest removed from the ring andhaving the extranuclear valences of carbons 2, 4, 5, and 6 otherwisesatisfied by hydrogen.

4. A 1,3-dithiane having on the four carbon a normal butyl substituentwith a carboxylic group on the carbon furthest removed from the ring,having the extranuclear valences of carbons 4, 5, and 6 otherwisesatisfied byhydrogen,. and having; onthe. 22 carbon, amonovalenthydrocarbon radicatfree from non-benzenoid unsaturation.

5.. Av 1,3-dithiane having on: the four carbonv a normal butylsubstituent with; acarboxylic. group. on the: carbon furthestremoved.from the ring, having the extranuclear valences of carbons 4,. 5, and 6otherwise satisfied by hydrogen and having the 2 carbon a spirocarbon,i. e., the sole carbon common to the dithane ring and to a second ring,saidv secondv ring. being. hydrocarbon of not more than eight carbons.

6. A compound of. the. formula s\ /s Aryl Aryl wherein Aryl denotes amonovalent mononuclear hydrocarbon radical with its freevalence stemmingfrom carbon of the nucleus.

7. Process wherein amember of the class consisting of6,8-dimercaptooctanoic acid and esters thereof is reacted with an oxocompound whereby a member of the class consisting of5-(1,3-dithiane-4-yl)pentanoic acid and esters thereof is: obtained.

8. An edible glycerid'econtaining a minor amount, effective to repressthe raneidificationof said edible glyceride, of a 5-(l',3'-dithiane-4-yl) pentanoic acid compound of the formula wherein R"is selected from. the class consisting of the carboxylic hydroxyl group.and groups hydrolyzable to such hydroxyl group and R and R when takenseparately are selected from. the classconsisting of hydrogen andmonovalent hydrocarbonv radicals of not more than eight carbons and whentaken together form a divalent hydrocarbon radical of not more thaneight carbons.

9. A 1,3-dithiane having on the four carbon a normal butyl substituentwith a carboxylic group on the carbon furthest removed from. the ring,having one extranuclear hydrocarbon radical of not more than eightcarbons on position 2 and having the extranuclear valences of carbons 4,5, and6 otherwise satisfied by hydrogen.

10. A 1,3-dithiane having on the four carbon at normal butyl substituentwith a carboxylic group on the carbon furthest removed from. the ring,having two extranuclear hydrocarbon radicals of not more than eightcarbons on position 2 and having the extranuclear valences of carbons 4,5, and 6 otherwise satisfied by hydrogen.

11. A 1,3-dithiane having on the four carbon a normal butyl substituentwith a carboxylic group on the carbon furthest removed" from the ring,having the extranuclear valences of carbons 4, 5,. and 6 otherwisesatisfied by hydrogen, and having, on the 2 carbon, two lower alkylradicals.

12. A 1,3-dithiane having on the four carbon 21 normal butylsubstituentwith a carboxylic group on the carbonfurthest removed fromthey ring, having the extranuclear valences of carbons 4, 5, and 6otherwise satisfied by hydrogen, and having, on the 2 carbon, twomononuclear aryl' radicals.

I References Citedin the file of this patent UNITED STATES PATENTS2,559,626- Jansen July 10, 1951

1. A CARBOXYLIC HETEROCYCLIC COMPOUND OF THE FORMULA
 7. A PROCESS WHEREIN A MEMBER OF THE CLASS CONSISTING OF 6,8-DIMERCAPTOOCTANOIC ACID AND ESTERS THEREOF IS REACTED WITH AN OXO COMPOUND WHEREBY A MEMBER OF THE CLASS CONSISTING OF 5-(1.3-DITHIANE-4-YL)PENTANOIC ACID AND ESTERS THEREOF IS OBTAINED.
 8. AN EDIBLE GLYCERIDE CONTAINING A MINOR AMOUNT, EFFECTIVE TO REPRESS THE RANCIDIFICATION OF SAID EDIBLE GLYCERIDE, OF A 5-(1,3-DITHIANE-4-YL)PENTANOIC ACID COMPOUND OF THE FORMULA 